Data and telecommunications consumer and infrastructure equipment such as portable handheld devices (e.g., mobile phones), consumer electronics equipment, hybrid and electrical vehicles, smart grid, and medical equipment, are driving growth for power management chips over the next several years. Power management semiconductor products include voltage regulators and references, power interface ICs, application-specific power management ICs, power transistors and thyristors, among others. Moreover, many of today's advanced data and telecommunications infrastructure equipment is driven by powerful processors with low core-voltage supplies. Power monitoring integrated circuits (ICs) monitor processor cores to ensure they operate within voltage tolerance specifications, allowing power and system engineers to maximize system uptime and optimize system performance.
Overview
A power monitor supply is provided and includes an electrical circuit including a comparator that receives a first signal at a first input pin, where the first signal is indicative of a current drawn from a power supply unit (PSU) that delivers power to an electronic component. The comparator substantially simultaneously receives a second signal at a second input pin, where the second signal is indicative of a voltage provided by the PSU to the electronic component. The second signal can be set to a predetermined threshold. An output of the comparator changes if a difference exists between the first signal and the second signal. The electrical circuit includes a variable gain amplifier that provides the first signal to the comparator, where a gain of the variable gain amplifier is set according to the predetermined threshold. In some embodiments, the variable gain may be achieved in the voltage path (e.g., rather than with a fixed voltage output). In various embodiments, the difference between the first signal and the second signal remains constant for a constant power drawn by the electronic component from the PSU.
In specific embodiments, a plurality of amplifiers may be included in the electrical circuit. The plurality of amplifiers measures a differential of a portion of the voltage from a reference voltage, and outputs the reference voltage if the differential is zero and otherwise adjusts the output reference voltage by the differential amount. The output may be provided as the second signal to the comparator. In some embodiments, the plurality of amplifiers can include a non-inverting unity gain buffer amplifier and an inverting voltage amplifier. The non-inverting unity gain amplifier may provide the portion of the voltage to the inverting voltage amplifier, and the inverting voltage amplifier may generate the second signal as its output. In some embodiments, the reference voltage is substantially stable and is provided by a voltage reference source. In particular embodiments, the portion of the voltage can comprise 10% of the voltage. In other embodiments, the reference voltage can be any suitable value lower than the Vin and within the rails of the amplifiers.
In specific embodiments, the gain of the variable gain amplifier can be set with a variable resistor, such as a digital potentiometer. The electrical circuit can further include a current sense amplifier that measures the current and converts the current to another voltage that is provided to the variable gain amplifier, which amplifies the another voltage according to the gain to generate the first signal.
In some embodiments, the comparator can include hysteresis, which can depend on the electrical configuration (e.g., design) of the circuit. For example, the hysteresis may be 0.5% of the power rating of the PSU, depending on the particular circuit configuration. In various embodiments, the predetermined threshold can be indicative of a power rating of the PSU. For example, the predetermined threshold can be set to indicate a maximum load on the PSU is approximately 100% of the PSU's power rating. In a specific embodiment, the output of the comparator is pulled high when the predetermined threshold is exceeded. The output of the comparator can provide a throttling signal and/or alert signal (e.g., warning signal, alarm signal, etc.) to the electronic component.
According to some embodiments of the electrical circuit, a response time of the electrical circuit is less than 10 μs. In a general sense, the response time of the electrical circuit can vary with (or be limited by) the bandwidth of the amplifiers and the propagation delay of the comparator, and can be configured to be any desired value, based on particular application needs. The voltage and the current are measured substantially simultaneously, and substantially all current and voltage measurements and comparisons are performed in an analog domain (e.g., without using digital computations, such as with a microprocessor). Being in the analog domain, the tolerance of the electrical circuit can vary substantially with the tolerances and offsets of its analog components.